An apparatus for locating positions on a surface of a structural member indicating the presence of elements within and below the surface includes a detector located in a housing and movable over the surface of the structural member. The detector has a scanning head mounted in the housing and a position measuring device within the housing for locating on the surface of the structural member a position of an element within the member and below its surface. An evaluation unit is located in the housing.
If a hole is drilled or a fastening member driven, for example, a nail or similar device, at a particular location into a structure, it is often necessary to ascertain if anything is present below the surface. For example, damage to electrical lines or to pipes carrying liquid within the structure can be avoided by such procedure. In the case of reinforced concrete structural members, it is important to know where the reinforcement is located and the direction in which it extends, so that, for example, drilling can be carried out at intended locations and not blocked by the reinforcement. Devices are known in the art for such a purpose. Utilizing known physical effects, such devices enable the interior of a structural member to be investigated. Such a device is disclosed in U.S. Pat. No. 5,296,807. With this device, magnetizable materials can be located within the structural member. In addition to devices for locating predominantly metallic elements, other devices are known, using ultrasonic waves or radar radiation for locating non-metallic elements within the structural member.
To find elements located within the structural member, the surface of the member is scanned with a point probe or scanning device such as the device disclosed in U.S. Pat. No. 5,296,807. When point probes are used, the location on the surface is determined and then a marking is affixed by hand with a pencil or a punch. In the scanning device of U.S. Pat. No. 5,296,807 a reinforcing member detected below the surface is displayed on a screen. The position of the screen is assigned to the effective location on the structural member surface by means of a measuring grid and a marking is placed by hand at the corresponding location. Manually marking the surface is laborious and subject to possible error. There are measurement probes having an opening through which a marking pencil can be inserted, provided at or in the housing. Because the pencil is guided manually and due to reading inaccuracies, the placement of a marking through an opening can lead to deviations from the correct location. When a measuring grid is used, the accuracy frequently depends on the care of the user when transferring the locations found.
Therefore, the primary object of the present invention is to avoid the disadvantages in the apparatus known in the art. Systematic random errors when locating elements within a structure or a structural member can be avoided. In accordance with the present invention, the apparatus includes a marking device for automatically placing a visible marking on the surface of the structural member indicating the location of an element scanned by the detector. The apparatus in the present invention for indicating locations on the surface of the structural member within which an element is positioned are found with the help of detection equipment including a scanning head, a position measuring device and an evaluating unit positioned in a housing. The evaluating unit is connected with a marking device interacting with the evaluating unit whereby a visible marking can be placed automatically on the surface of the structural member at the location of the elements detected in the scanning operation.
The marking device of the present invention can be activated or operated automatically at the location of the element, such as the reinforcing member located below the surface of the structural member. The marking can be placed on the surface of the structural member or on a sheet of paper positioned on the surface. There is no longer an offset between the location of the elements scanned and the location marked, since the marking device can be activated only at the effective location. For this purpose, the evaluating unit of the detector equipped with a memory device containing the location data is supplied by the position measuring equipment along with the information concerning the elements found below the surface of the structural member stored in the evaluating unit. The location data and other information, contained in the memory, can be used at a later time for controlling a separate marking device equipped with a position measuring device identical to the detector. The location data, measured by the position measuring device of the marking device, are compared constantly with those of the position measuring device of the detector. As soon as there is agreement, the marking device is activated automatically for producing a visible marking.
In a preferred embodiment of the invention, the detector and the marking device are combined into an apparatus unit which is moved at the same time over the surface of the structural member. Based on the intended direction of movement, the marking device is positioned at a defined distance behind the scanning head and, after the unit has moved by the distance between the scanning head and the marking device, the marking device is activated automatically at the location of the element below the surface of the structural member as scanned by the detector. Such a unit has the advantage that only a single measuring device is required. Possible deviations resulting from different location measuring devices of the detector and of the marking device are reliably avoided in this manner.
The marking device may include a punch-like plunger producing depressions at the desired locations on the surface of the structural member. Preferably, the locations of the elements scanned below the surface are marked in a contactless manner. Accordingly, the marking device includes at least one container for a marking liquid, an applicator with at least one applicator nozzle, and a triggering device.
The marking device may comprise one or more applicator nozzles which can be moved transversely to the direction of movement of the apparatus in accordance with control information collected by one or more sensors disposed in the scanning heads. In an alternate embodiment of the invention, the applicator nozzles are rotatably mounted on a planar paralleled surface of the structural member. To apply a visible marking, the angle of rotation of the applicator nozzle or nozzles can be adjusted as a function of the control information supplied by the one or more sensors disposed in the scanning heads.
Actually, a single applicator nozzle would be sufficient for marking the surface. It has proven, however, to be advantageous to arrange several applicator nozzles in cellular form perpendicular to the intended direction of movement of the apparatus. In an advantageous embodiment of the invention, the number of applicator nozzles corresponds to the number of sensors in the scanning head. With the applicator nozzles arranged in cellular form, they cover a greater region perpendicular to the direction of movement of the apparatus. When the number of sensors and the number of applicator nozzles is the same, an applicator nozzle assigned to each sensor can be triggered separately. A larger area of the surface can be examined in a shorter time period when the apparatus is arranged in this manner. The orientation of the elements positioned below the surface at an angle to the direction of movement can be checked and indicated accurately. Elements extending parallel to the direction of movement of the apparatus are generally detected by at least one of the sensors and can be indicated by the applicator nozzles that follow. Since a surface is generally investigated in a grid-like fashion with the scanning movements extending perpendicularly to one another, the elements positioned below the surface are located in every case independently of their extent relative to the surface of movement of the apparatus and their presence is not represented by visible markings on the surface.
With the sensors arranged replaceably in the scanning head, the apparatus can be changed over for different scanning operations. The scanning head, instead of being equipped with magnet sensors for finding magnetizable elements in a structural member it can also be equipped with ultrasonic sensors or with a radar sending and receiving device, for detecting non-metallic elements.
Since a separate container for the marking liquid is connected to each applicator nozzle, different types of visual markings can be applied, for instance, certain additional information, such as information concerning the character of the element located below the surface, can be provided in a coded form by different colors. In this way, it is possible to tell whether it is a reinforcing member, an electrical line or a water pipe.
In an advantageous embodiment of the claimed invention, the marking device is arranged on one hand for visibly marking the location of a detected element, and, on the other hand, for reproducing additional information, such as the depth at which the element has been observed. This can be accomplished due to the fact that the applicator nozzles are triggered in such a manner that the marking device gives the orientation of the element found below the surface, and, in addition, is in a position to draw numerals, letters, symbols, color markings and the like on the surface.
It is advisable to connect the evaluating unit with an input unit, such as an alphanumeric input field for the input of threshold values and the like. With such an arrangement, the marking device can be triggered in such a manner that a marking is produced only if the distance between an element located and the surface is less than a specified threshold value. It is proven to be advantageous to place the marking device in a separate housing detachably connected with the detector housing. Further, the marking device can have its own power supply. Advantageously, however, the power is supplied by the power supply of the detector. Further, the connection required is provided by appropriate coupling over connection interfaces at the housing of the detector and at the marking device. By separating the two devices within the housing the detector can be used independently of the marking device. The user also has the option of initially acquiring only the detector. Later, when he finds that he would also like to use the advantages of the marking device, there is the possibility of supplementing the existing detector device to gain an advantageous complete system.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there is illustrated and described a preferred embodiment of the invention.